Abstract: Hydatidosis is one of common diseases between human and animals. Different intermediate hosts distribute this dangerous disease in a region. The aim of this study was to determine the prevalence of hydatid cyst in slaughtered animals in northwest Iran. In this cross-sectional study, a total of 5381 animals (928 cattle, 243 buffaloes, 3765 sheep and 445 goats) were inspected macroscopically for hydatid cyst. Prevalence rate of hydatid cyst in cattle, buffaloes, sheep and goats was 38.3, 11.9, 74.4 and 20%, respectively. In all cases, its prevalence in female cattle and sheep was more than male (p<0.001). Most condemnation cases were seen in lung of sheep (13.4%). It appears that sheep are the most important intermediate hosts for Echinococcus granulosus (E. granulosus) in this area.